A number of applications exist for chemical analysis techniques for detecting the presence and concentration of known analytes in test samples. Such applications include testing and monitoring of foodstuffs, beverages, feeds, soils, plants and water supplies for pollutants or controlled substances. The analysis process typically involves collection and preparation of chemical samples, analysis of the samples in an analytical instrument and recording of the results of the analysis. A number of steps may be involved in the preparation of each sample, including dilution, addition of reagents and transport of the sample to the analytical instrument. Depending upon the type of analysis to be performed and the analyte to be detected or measured, various instruments may be employed. Moreover, various test methods may be used for certain analytes involving parallel operations in multiple instruments.
Automation of chemical analysis equipment has permitted sophisticated analyses to be performed at greatly increased speed without sacrificing the quality of analytical results. Such automation typically involves arranging a number of peripheral devices, such as samplers, diluters, injection valves, pumps and other sample preparation apparatus to serve an analyzer where test samples are analyzed for the presence and concentration of various analytes. Some known systems include a central computer system or other signal processing unit for coordinating the operation of the various components and for storing and tabulating test results. Such systems are described, for example, in U.S. Pat. Nos. 4,158,545, 4,166,095, 4,366,119, 4,459,265 and 4,483,927.
In known automated analysis systems test samples are typically arranged in sample cups. In certain known systems a series of such cups is advanced along a path where the sample is prepared for analysis, such as by adding appropriate reagents. The series of cups eventually reaches an analysis station including an analyzer, such as a spectrophotometric instrument, where the sample is analyzed. In other known systems, sample cups are arranged in an array and samples are aspirated by a transport system and delivered to an analytical instrument. In either case, results of the analyses may be collected and recorded in a central processing unit for later printout or display.
While such systems represent a considerable improvement over manual analysis techniques, they are not without drawbacks. For example, known automated chemical analysis systems typically associate a number of peripheral devices with a single analyzer. Such systems may approach continuous usage of the analyzer by coordinating preparation and delivery of subsequent test samples by the peripheral devices during the time a previous sample is being analyzed. However, where the time required for sample preparation and delivery is much less than the time required for analysis, the benefit achieved by such systems is ultimately diminished as the peripheral devices become idle.
A further drawback of known automated chemical analysis systems is the space required for the associated analyzers and peripheral devices. Because each analyzer is typically served by dedicated peripheral devices, the space required for the overall system is multiplied where several analyzers are present, each with its associated peripheral devices. This problem is particularly acute when analyzers and peripheral devices are incorporated in a mobile analytical laboratory for performing on-site analytical operations, such as for environmental pollutants. Such mobile laboratories are often housed in a specially equipped vehicle in which benchspace is especially limited. A particular need presently exists for improved automated chemical analysis systems for on-site compliance monitoring of U.S. Environmental Protection Agency standards, such as by flow injection analysis (FIA) and ion chromatography (IC), Such applications require complex analytical systems capable of performing analyses quickly and reliably, but that occupy a minimum of benchspace. Moreover, such systems should be capable of testing for a range of analytes through various methods, some of which call for parallel analyses to be performed in different types of analyzers (e.g. FIA and IC). Finally, they should be capable of facilitating scheduling of such tests and recording test results as they are available for display and printout.